The mysterious protocols: SPF, DKIM and DMARC explained

Email is an ancient thing, it was born much longer before the Internet.

The first email system was born in 1965 at MIT. At that time email communication was limited within the boundaries of a single mainframe, those huge and very expensive and delicate multi-user computers that occupied entire air-conditioned rooms and required continuous supervision.

In 1971, the first transmission of an email between connected computers happened. It was a small step for a single email, but a first huge step for humankind.

In 1982, the SMTP protocol was born, this is the protocol we still use today to exchange email on the internet.

The main issue about email (and SMTP) is that, being born in a collaborative environment where security wasn’t an issue at all, being designed at a time where abuse was not even an theoretical option, the protocol did not have any security at all among it’s design requisites.
No authentication of the sender: anybody could pretend to be anyone.
No confidentiality: messages were exchanged and stored in clear.
No integrity checks: manipulations of the email content along the path could not be prevented or even detected.
No protection about unsolicited messages: anybody could send any amount of email to any recipient.

Then email became popular and these issues started quickly to pop up.

It became clear that we needed to do something in order to address this lack of security in the protocol. Nobody had thought about it earlier because nobody envisioned that email would become what it is today: the main form of electronic communication that our societies are based on, something that all organizations, businesses and individuals rely on every day in order to run their lives.

As we all learned the hard way in the following years, adding security afterwards is much more difficult than putting it in at design time. This is one of the most important principles of GDPR: if you want real security you need it by design.

Adding security as an afterthought is hard. It is even harder if you have to guarantee backward-compatibility. Email is the most clear example of how hard is to add security to something that is already deployed worldwide—where you have to guarantee that email can still be exchanged with servers that are not upgraded to the new standards.

This is where the acronyms that are in the title of this article come into play: SPF, DKIM and DMARC are three standards that have been added to the email in the attempt to make it more secure.

SPF has a very simple task: prevent domain spoofing. Your organization can declare to the world a subset of IP addresses authorized to send email on behalf of your organization’s domain. By defining this policy, you can prevent malicious actors sending email pretending to be your organization.
The configuration of an SPF policy is very easy and relatively risk-free: you just need to map all the IP addresses that your organization uses to send email. A little effort for what you receive in exchange, and if you correctly enumerated all your legitimate IP addresses you send email from, no email will get lost.
SPF isn’t perfect, though, and it is not sufficient to prevent all types of spoofing, but it is still much better than nothing.

DKIM has a main purpose: guarantee the integrity of the email content. Integrity means that the recipient can detect if the email has been modified or tampered with along the path. This is done through an electronic signature: if the signature is valid, you know that you can rely on the content of the email. If the signature is invalid, then the message has probably been tampered with. This signature is automatically added and checked by mail servers, and the user doesn’t need to do anything.
Setting up DKIM requires a little more effort than SPF but it is safe: if you misconfigure it, email will not get lost.

SPF and DKIM still don’t completely solve the phishing problem. Email is a little bit like a plain paper letter: the sender and the recipient written on the envelope are used for the delivery, but the recipient does not see the envelope. The recipient just sees the letter inside the envelope, and in that letter the name and address of the sender can be spoofed. Basically, the email client shows the sender that is written in the letter, not the one on the envelope (which can be protected with SPF).

DMARC has been designed exactly for this purpose: making sure that the sender that your email client shows is reliable. This is done by publishing a DMARC policy that instructs the recipients to check if the sender displayed to the recipient matches either with SPF or DKIM. The email must be sent from an authorized IP address for that domain (SPF is ok), or it must be signed with a legitimate key of that domain (the DKIM signature is ok), otherwise it will not be delivered.

DMARC must be configured on a domain by domain basis by the email administrator of the sending domain. It provides great protection against spoofing and impersonation, but the configuration is not straight-forward and mistakes in the configuration can lead to email loss. Therefore, configuring DMARC must be done with expertise, without improvising.

There are other standards that have been introduced in email, like TLS (to encrypt the email in transit) and S/MIME or PGP for end-to-end encryption. These are things you don’t need to care about. TLS is automatically managed by mail servers. S/MIME and PGP have minuscule adoption because of the complexities related to the key management by the end users.

Should you care about SPF, DKIM an DMARC for your organization? Yes, you should.
Start with SPF, then proceed with DKIM and finally evaluate DMARC.

These configurations will not solve all email security problems, but they will make your email communication much more secure and reliable.
Keep in mind that under the hood email is much more complex than it looks on the surface, so consult with an email expert in order to be effective and avoid trouble.

New wave of EXCEL 4.0 malware campaigns abusing FORMULA macro function

VBA has been introduced in Excel 5.0. Before then Excel only had XLM macros, which are still supported today.

XLM macros allow writing code by entering statements directly into cells, just like normal formulas. In fact they are called macro-formulas.

In case you are curious, the reference document of the Excel 4.0 macro functions is here.

There are a few statements among these macro-formulas that allow executing malicious code, these are named EXEC, RUN and CALL. Last month, in April 2020, a wave of malware abusing these calls has circulated.

In May we’ve seen a new wave that apparently still abused XLM macros but without calling EXEC, RUN or CALL. At the time we got them, most of these samples had a 0 detection rate on virustotal, so they seemed to be worth investigating.

Some of these files were using additional tricks to confuse the analysis, like putting the macros in “hidden” sheets. Some others used “very hidden” sheets, some were protected with the “VelvetSweatshop” password (which is a trick used by Microsoft to define read-only documents). There is also a great variability in file names and email campaigns. I won’t waste time on these details and will get straight to the point.

Here is what you see when opening one of these samples:

macro promt

This is the macro prompt shown by Excel when opening the document

This is the usual Macro prompt from Excel. Nothing unusual.

Then this is how the document appears after either accepting or declining the “enable macro” prompt.

The malicious document as soon as it is opened

Again, nothing unusual here. This is just one of the samples, there are of course many variants but, again, we don’t care.

In this case the sample has two visible sheets. As I said before some of the sample have invisible sheets but this is also not important for our analysis.

What all these samples have in common is the abuse of the FORMULA macro-formula. The recursive naming may create some confusion so let me provide a bit of clarification: just like any other formula statement (like IF or SUM for example), the statement FORMULA can be entered into a cell in the form of a formula. This particular statement happens to be named FORMULA itself.

What does this FORMULA statement do? It enters a formula in the active cell (or in a reference). Basically what is given as a parameter to this call becomes a fomula.

Indirect formula generation if you wish and, yes, it is dangerous as it sounds.

While it is quite clear that the following formula may be dangerous

=EXEC("C:\tools\nc.exe 443 -e cmd.exe") 

it may not be immediately clear that the following one is


An this is basically how these malicious samples behave: they crate a formula by gathering data from lots of different cells and making some transformations. Then they apply the formula by using the FORMULA.FILL statement (or one of it’s variants, see the functions reference linked above if you are interested).

The exact text of the FORMULA is built at runtime and this ensures obfuscation which seems to be effective given the zero or very low scores that these samples got on Virustotal.

This is a glance of what you see by analyzing one of these samples with Decalage‘s olevba:

Tiny portion of the olevba output for one of these samples

I’ve highlighted the FORMULA.FILL function call. There are tens of these calls in any given sample.

We are not interested in reverse-engineering each sample in order to find out the details of the behavior. As an email security company we focus on the methods and the tools used by the attackers rather than on the specific malware variant.

Our job is to block these threats on the gateway, we know that the approach of recognizing known malicious stuff is not effective and therefore we focus on removing the tools that the attackers use.

The philosophy of our QuickSand sandbox is more similar to a firewall: when our systems see a pattern like these they don’t really care about reverse-engineering the actual behavior, they don’t even care about recognizing whether this is a known malware variant or a new one.

Whether it is direct or indirect, any way of executing stuff is not allowed for documents delivered via email. This approach is less prone to evasion and it is proactive: it blocks current and future, known and unknown variants.

The low detection rate of these samples on virustotal and on many sandboxing services based on virtualization confirms that in order to be effective with ever-changing threats this is a better approach.


Rodolfo Saccani / Security R&D Manager @ Libraesva

Exploiting Fear as a Threat Actor

One of Libraesva’s Security Researchers recently discovered, along with other security vendors, targeted phishing and whaling campaigns all based around the Coronavirus outbreak, we don’t believe in playing on the fear, but its always good to see how these attacks work and why they work.

Figure 1 shows the email in question we received and blocked, the attackers in this case pretended to be the director of Milan University, warning internal users of the outbreak and steps to take to prevent further spread. As it turns out in fact, the email was spoofed and sent by a trusted sender from a fellow university, typical whaling attack, instead this time the call to action wasn’t transferring funds, but instead helping fight this infectious disease.

Figure 1 – Email Spoof of Director of Milan University, sent from a University of Bologna compromised account.

The interesting thing about this attack is that the sender of the email is trusted by the university and states on many occasions about the dangers of the virus 2019-nCoV as a respiratory epidemic, the call to action here is to quickly, look into the attached document which is a simple docx file with a link shown in Figure 2.

Figure 2 – The Document “Documento condiviso dell’Universita di Milano.docx” Attached.

Here in Figure 2 we can see the document in all its glory, feigning the need to access the file via a link which takes you to the screen in figure 3, obviously trying and failing to spoof an Office 365 login page

Figure 3 – The landing page when following the link from the attached document

Once Download file is selected you can clearly see when this becomes a true phishing scam, asking for passwords.

Figure 4 – After selecting download file, we can clearly see credential harvesting fields.

The Coronavirus is a great opportunity for any hacker worth their salt, but there are a few essential things considered when Libraesva decides that this is malicious

How we spotted it:

Whaling Protection: Our first observation was that the Director of Milan University is in our Business Email Compromise protection list, so we took additional checks to stop this user’s name and email being used against their own organisation. Effectively protecting this specific customer from any BEC/Whaling Attacks

Adaptive Trust Engine: Next we saw that the trust between these two organisations was quite high using the Adaptive Trust Engine’s relationship monitoring, but the trust between the two individual user’s was low, we didn’t let the organisational trust get in the way of understand the true nature of the email.

Sandboxing: Libraesva’s uniquely designed and built-in sandboxes disarm any docx, xlsx and pdf documents creating zero risk files meaning this attack, even if delivered to user’s would be unable to ex-filtrate information due to there being no links, no code, nothing in that document.

To Conclude:

Hopefully you learnt a little bit about how these business email compromise attacks look, and how threat actors work off the fear that the public have, Libraesva spotted this early and stopped it from reaching anyone. Thanks for reading and let us know if you have any questions at all.

What is an Evasion Technique?

What exactly are Evasion Techniques?

Evasion techniques are what malicious payloads use to avoid detection from Sandboxing services, Malware authors have two priorities when creating malware, being silent and being deadly, getting as much as they can for as little effort as possible.

We thought it’d be wise to talk about how effective these evasion techniques are against traditional sandboxes and how we as Libraesva handle them in our Email Security Gateway.

My Top Evasion Techniques

Polymorphic Code – Code commonly used to bypass pattern and hash based detection, the malware modifies itself in delivery to other locations, thus effectively being really hard to track and detect. Polymorphic attacks don’t have a single detectable signature, Shikata ga nai meaning (“It cannot be helped”) is a popular polymorphic encoder inside metasploit’s framework making it relatively easy to turn malicious code into polymorphic code.

This technique specifically involves encoding the payload in some fashion, then placing a decoder to undo that mess in front of the payload before sending it. When the target executes the polymorphic code, the decoder is run first which rewrites the subsequent payload into its original, malicious and nasty form before executing.


User and System Interaction Detection – Users interact with computer systems in different ways, they are unpredictable in some essence, which makes them obvious to spot. They press keys on a keyboard in a specific way, scroll with the mouse wheel and click on things with the mouse. However, there are no interactions this bespoke in a Traditional Sandboxed environment. Malicious hackers teach malware to wait for a specific user interaction before exhibiting their malicious behaviors.

Examples of this is executing after you scroll to a particular place within a word document, using paragraph codes in Word files, Trojan.APT.BaneChan activates only after a certain number of mouse clicks are made by a user, other examples of this are timing the speed of the mouse movement and halting all code unless the mouse moves at a human’s speed.

Other system checks malware perform can be the Core Count technique, allowing malware to find differences between virtual and physical system CPU cores. Many sandbox vendors hide their system settings and hardware so when the system check is done, the coded malware is returned with null, which is a good sign for malware to stop running.

Lastly one of my personal favourite checks is the reboot check, where the malware checks to see if reboot triggers are executed in full, Sandboxes can try to emulate a reboot by logging out and back in as users and sleeping the system, however these never fully run all reboot triggers. The main reason this is such a useful evasion technique is due to most Sandboxes not being able to survive true reboots. So if you make your malware run after you switch the machine off and back on, you’ll rarely detonate on a sandbox environment!


Obfuscation of Internal Data – Some sandbox evasion techniques consist of malware being allowed to change and encrypt, similar to the polymorphic examples referenced above, however this is more simple to run and can help you target attacks to specific organizations.

Fast Flux is a technique of changing DNS names and IP addresses rapidly, mainly used by large botnets that aim to hide themselves from phishing detection systems. It allows malware to bypass blacklists that most security solutions create. Some malware is known to change its domain names as fast as every 10 minutes.

Data Encryption can be a quick way to win big, encrypting API calls so that traditional sandboxes can’t read the APIs, usually multiple encryption keys are used to protect the malware from brute force decryption detection.


How does Libraesva’s Sandbox get around this?

Traditional sandboxes are in a constant fight to catch up with malware authors in understanding their evasion techniques and the malware’s specific behaviors. This is sometimes known as a cat and mouse game.

Malware constantly evolves and security teams constantly research.

Libraesva’s QuickSand Sandbox deploys a pragmatic method to stopping these threats by looking directly at the evasion techniques and signs that things could be malicious, not the malicious act itself. QuickSand is a preventative sandbox which utilizes evasion techniques to protect you and your users.

Our Head of Research and Development Rodolfo Saccani told me once “A man walks into a bank with a mask over his head, does the bank care what the man plans to do? No, they’ve already alerted the police.” This way of explaining evasion techniques and how to use them as identifiers sticks with me and helps me define what Libraesva’s threat approach is like, we look less at who he points the gun at or why is he asking for the bank’s money, but more at the identifiers of the man being malicious i.e. the mask over his head and the gun in his hand.

QuickSand directly looks at things within documents that scream “I’m a bad document” an example of this is if a word document you’ve been sent has JavaScript embedded inside of is, we don’t care what the JavaScript is doing, we’ve already cleaned the document and disarmed it of any active java code because in a typical working environment, this isn’t a legitimate use of JavaScript.

QuickSand is also available directly on the appliance, meaning your files and data don’t leave the Libraesva appliance, we aren’t sending anything to a cloud virtual machine sandbox, we process everything in seconds on your own Libra machine.

So next time you are cleaning up a breach or patching holes in your network, try finding new ways to prevent threats, preferably looking at them before they are detonated, to try and find patterns and warning signs of them being malicious!

Did I mention that our sandbox is included in Libraesva’s Email Security Gateway?


Thanks for reading this! If you think it was beneficial let me know, and provide any feedback you can to me and the team over on LinkedIn or YouTube!

Email trojan horse: application/html entity

We just discovered a new trick that is currently being used to slip malicious html files through email security solutions and,  in some cases, through antivirus engines.
The trick is quite simple: declaring an email entity as “application/html” instead of “text/html”. “application/html” is an invalid type and this allows it to slip through some checks.



Emails are composed of many “parts” called “entities”. Each entity has a content-type header that declares the type of it’s content (the textual or the html portion of the email,  the images contained in the message, the attachments which can be of many different file formats). For example the html portion of the mail has content-type “text/html”, the text part is declared as “text/plain”, an image can be “image/png”, an attached office document can be “application/msword”, and so on. There is a list of valid types and “application/html” is not among those.

What happens if you declare an invalid content type? It depends. Email clients try to be helpful and tend to consider as valid the types they don’t know, but security solutions and antivirus engines may behave differently. They make specific security check that depend on the content and when faced with a content type they don’t know in some cases the end up ignoring or not analyzing properly the content of these entities. At least this is what happens with the entity type “application/html” that we tested.


Samples in the wild

The samples found in the wild are delivering html files that, as soon as they are opened, redirect to a malicious site (through a meta tag). These very small one-line html files are attached to malicious emails inside an entity of an invalid type “application/html” instead of the correct type “text/html”. All the email clients we tested (including the major webmail services) show these files as normal attachments but all the email security filters we tested (including those of the major wemail services) could not find malicious links contained in these html files if the entity was “application/html”. While they did detect them if contained in a normal “text/html” entity, they could not detect them if the entity type was changed to “application/html”. This trick is actively being used in the wild, this is why it is appropriate to go public with these findings.


Our testing

In order to assess how these entities are managed by email services and clients, we created two email samples with an html attachment containing a link to a malicious website. One of the samples has the entity type changed to “application/html” instead of the normal “text/html”. This is the only difference between the two samples.


The sample with the “application/html” entity was delivered as clean in the inbox of all the systems we tested (including the major email providers) while the very same email with the entity of type “text/html” was correctly classified as dangerous. Some checks are clearly missing when the entity type is “application/html”.

All it takes to create a “stealth” entity is to change the word “text” into the word “application” in the content-type declaration.


All the email clients (including major webmail services) allowed the user to open the html file contained in the “application/html” entity.

Here is the malicious html file inside an application/html entity sent to Gmail:

Clicking on the attachment, it is displayed and offered for clicking.

Here is the same malicious html file sento to Gmail in a normal text/html entity:

The text/html entity is properly analyzed and classified as dangerous, the application/html entity is not.


Tests with actual malware

We performed a second test, by embedding a real sample of emotet in the html attachment (inside an href tag). With this sample the results varied: major email providers correctly detected the threat while some email filtering solutions didn’t.


The image above shows how we embedded emoted inside the html file.

These samples have been also tested with major and widely used antivirus engines: some of them did not inspect the “application/html” entity even if they could correctly detect the same sample in a “text/html” entity.

The target of this post is to raise awareness so there is no point in naming products here. We just show a test performed with an opensource antivirus engine.


In the previous image we have two samples containing emotet embedded in the html file.

entitytext.eml had a normal “text/html” entity while entityapplication.eml had an entity of type “application/html”. The first command (diff entitytext.eml entityapplication.eml) shows that the only difference between the two emails is the word “text” replaced with “application” in the content-type declaration.

As you can see the antivirus detected emotet in the first sample and didn’t detect it in the second. This test used clamav but the same test with major commercial antivirus engines produced similar result.

The sample entityapplication.eml uploaded on virustotal has been classified as malware by 9 engines on 57:


From an email security gateway point of view, blocking emails containing entities of type “application/html” is probably the wisest thing to do and this is what we are currently doing.

This is clearly an attempt to evade security inspection by pretending to be some kind of unkown application-specific data, inducing to perform only broad and general security checks (for example clamav does not decode base64-encoded data embedded in the href tag if declared as “application/html”) while, at the same time, inducing the email client to offer the file to the user as a normal html attachment.

An attempt to evade analysis is a strong signal about the malicious intention of the sender and should be penalized accordingly.

This threat has been added to our email security tester, a tool to assess the performance of emails security protections. This means that you can easily test, right now, whether you are protected or not from this and other common email threat vectors.

Five things admins forget when using Libraesva ESG

I get it, you’re a hot shot Libraesva ESG admin who knows everything about the system, but even the best of us make mistakes and forget the basics, even me! In a recent certification course we held in the UK we discovered some fairly obvious shortcomings in basic configuration and management of the solution that most admins adhere to and we thought right now is a great time to inform you of them, so you can continue being a pro Libraesva ESG admin.

  • Libraesva ESG does the leg work for you

Libraesva ESG is built from the ground up to be set and forget meaning you really don’t need to reinvent email security, some of the first things administrators like to do is change the anti-spam scoring, the default rule sets and even switch off the sandboxes (I know, weird right!?). However, this isn’t optimal or even required at all.

Libraesva ESG comes setup out the box in its most optimal and secure mode, it links directly back to Libraesva HQ to get up to date analysis statistics and rule sets so you don’t have to, at most the Libraesva system will need input from users in the quarantine section and threat submissions. The Libraesva team are constantly updating the ESG platform, rule sets, and our security engines to make your life easier and lessen the management load of you and your admins.

  • Always check the Technical Message Details

The first place you should always be checking is the Message Technical Details section, here you can find the Dangerous checks and the Anti-Spam analysis, in these sections you will find all the information and rules that were parsed against the email you are analysing. You can see all of the anti-spam rules, QuickSand and URLSand status and even Virus Signatures.

We want administrators to understand completely and transparently why we did or didn’t block something, if we are wrong then you can tell us, if we are spot on, you now know exactly why we stopped a threat or email.

  • Threat Remediation is here for you

If you’re one of the lucky ones who are on Office 365, Exchange or Zimbra email servers, you have unadulterated access to Threat Remediation, a free tool used in the event of a categorisation fail on Libraesva’s side, if something slips past Libraesva, which rarely happens, you can jump into the reports section and immediately remove the threat or unwanted email from your user’s inboxes.

You have a few options after you’ve re-mediated the threat, you can analyse it yourself using number 2 and then if you deem the email to be safe, you can simply release the email back to your users.

  • Recipient Verification handles Licensing

So licensing isn’t that complicated in Libraesva, but here is a quick rundown,

Libraesva ESG Yearly Subscriptions licenses unique email addresses, this means aliases, mailboxes, distribution lists and all other unique email addresses will take up a license, Secondly a license is only consumed when Libraesva accepts mail on its behalf and scans it.

So if you don’t verify or validate who the recipients are within your organisation, Libraesva will accept email to any address that is referencing your domain, an example:

[email protected] doesn’t exist, but Libraesva ESG will accept this email and scan it because the system isn’t verifying recipients, thus using a license. So always remember to switch this on, link the ESG to your LDAP or O365 system and validate those recipients! A full guide on how to link LDAP or O365 can be found here and here respectively.

  • QuickSand’s sanitised files can be recovered

When you look into your quarantine report at the end of a long hard day you might see something that looks odd, a quicksand message in your quarantine with a score lower than your spam score threshold, don’t panic. This is just telling you that you have the original pre-sanitised and possibly unsafe document, there ready to be released if you need it.

See the way QuickSand works if you aren’t familiar is that it takes active content on PDFs and Office documents and tries to completely remove the content and sanitise the document, leaving you with a plain old PDF or Office document with no content that can cause harm to you or your users, this could be disabling links, removing JavaScript and disabling macros.

However sometimes documents will no longer function, or you might want to access the JavaScript hidden in a PDF for reasons only your organisation know, and we give you that access in the quarantine report.

  • In Conclusion

Don’t panic next time you see a quicksand message in the quarantine, these are still getting delivered in a sanitised and safe method, And always remember to leave the heavy security lifting to us and the software, we are here to help make sure the performance of the system is always exemplary.

Thanks for reading! Make sure you follow us on LinkedIn and YouTube for more blogs, videos and other useful content!

10 very practical suggestions for choosing an email archiving solution

What makes a good archiving solution? Count 1 to 10:


1- No vendor lock-in

email archiver dashboard


Archiving email is a long term commitment, you need to think long term and make sure that you will be able, in 10 or 20 years from now, to autonomously, easily and reliably make use of your email archive.

If the data is stored in a proprietary format you will not be able to move it to a different archiving solution, you may not be able to even read it without the software provided by the vendor, who may not be around anymore at that time.

This is why it is important that your emails are stored in an open format, a format that you can read with open tools and without any special knowledge: your current staff may not be around at the time you will need to recover the archive.

In 10 or 20 years from now any proprietary tool may not work anymore on whatever will be a current operating system, if it does you may encounter technical issues for which you need the support of a vendor who does not exist anymore. When it will happen you will probably be in a hurry and will find out that everything is much more complicated, expensive and time consuming than you expected.

Having all the archive in an open and standard format, that you can easily recover without any specialized tool is crucial. The best solution allows you to retrieve the email you are searching for with the bare minimum of the tools: a file manager.

Our email archiver stores plain EML files inside Zip files, one Zip file per day or every 4000 email. The filename of the zipfile clearly tells the archive date so that the minimum tool you need to search and recover email is a filemanager.

Why this choice? The Zip file is a standard format, supported now and tomorrow by a big number of open tools. It provides compression, de-duplication and state-of-the-art encryption (AES256). There is no need to re-invent the wheel, unless you are aiming to lock your customers in a proprietary format.


2- Legal validity

RFC3161 certified timestamps

Certified timestamps

It is important that your stored email can be used as a legal evidence, should you need it. This means being able to legally prove that:

  1. the email has been received and archived at a specific time
  2. it has not been modified afterwards

There is a standard, formalized in RFC3161, called “certified time-stamping”. This is an open an documented standard, supported by many open tools that can be used for the verification of authenticity.

Our archiver ships with an embedded certification authority that certifies every single email that is stored. This is done automatically out of the box, no configuration is needed.

Whenever an email is retrieved from the archive, the archiver also automatically verifies its integrity.

Legal value should just be, without any configuration burden, and this is the way we designed it.


3- Multiple copies

email archiver volumes


Storing all of your stuff in a single place is not wise. This applies to backups and especially to email archiving, which is much more than a set of backups. You must be able to store multiple copies of your archive in multiple locations, automatically and continuously.

Our archiver supports an unlimited number of volumes of different types: local disks, LAN drives, object storage (supporting virtually all providers and protocols), ftp and sftp.

Email is automatically stored in multiple copies on different volumes which can exist in many different geographical locations (archives are encrypted with AES256). You can also define different retention times for different volumes. For example you can decide that a local volume stores the last 5 years while a remote object storage volume stores the last 20 years worth of email.


4- Usability

email archiver outlook addin

Outlook Addin

Email archiving is not just for compliance, it’s also a tool to improve the productivity of the company. Users should be able to use it for retrieving their own archived email. In order for this to be achieved, the user interaction must be straightforward.

We provide an outlook plugin (it works also in OWA and O365) which can be automatically deployed, an iOS and an Android app, a webapp. Users can not only work with their own email archive: delegation is supported and saved searches can be shared with other users providing an easy way to delegate access to a well specified subset of email.

Slow mail server? The archiver can automatically delete old email from your mailserver, after having verified that it is safely stored in the archive.

The archiver provides a full-text search engine that is much faster than any mailserver. In terms of user interactions the standard definition of what is perceived as “instantaneous” is below 100ms and this is the response time of a standard search query on a big archive of millions of email messages on our archiver.


5- Privacy

Privacy management

OPT request for privacy access

Of course you need to make sure that privacy is properly enforced, that email can be seen only by the legit owners and that nobody else, including administrators if that’s your policy, can read it.

On our archiver a tenant can be protected by a privacy officer, which means that also the administrator must ask for authorization in order to access email contents.

The authorization process is fast and straightforward: time-based OTP (think Google Authenticator). Six digits that can easily be dictated over the phone for a lean but strong privacy enforcement. Once obtained the authorization everything is logged and reported back to the privacy officer.


6- Flexible ingestion

Ingestion options

Ingestion options

The email archive will follow you over time. The archiver system must be very flexible in terms of ingestion so that you can easily move to different email systems, migrate to or from the cloud, without having to re-think your archiving strategy.

Supported ingestion methods must include SMTP journaling, SMTP forwarding, IMAP, POP3, native O365 and Exchange connectors.

Import of PST or EML archives should be supported as well as exporting to the same formats.

We’ve also implemented batch import for a painless bootstrap: you can provide entire disks full of PSTs or EML archives and they will be imported automatically no matter how big they are.


7- Integration

API documentation

API documentation

A full API is important when you need to make some integrations with your infrastructure, especially if you are an ISP or an MSP and you want to integrate the email archiving service with your existing web panels.

All the features that our archiver provides are available through a complete REST API. It is so complete that all of our front-ends (web-app, the mobile apps and the outlook plugin) only interact with the archiver through the API, so all functionalities are naturally exposed via API.

You can use the archiver in complete headless mode if you want, you can perform any integration you will ever need.


8- Ease of deployment

Current version

Current version

Cloud? On-prem? That should all be covered. Who knows how your infrastructure will evolve in 10 or 20 years.

A virtual appliance provides the maximum flexibility: you can run it in the cloud, on premise, you can easily migrate it around and increase resources over time, you have no proprietary hardware to replace, move around or repair.

The virtual app automatically updates itself, new features are automatically installed.


9- Archiving flexibility

Archiving rules

Archiving rules

You should be able to choose what you want to archive and what you don’t want to archive. You should be able to choose different retention times for different emails: newsletters? One year may be enough. Lawyer? 10 years minimum. And so on.

Talking about lawyers: legal hold is the capability of locking some email (for example related to a legal case) until a specified date. This is what you need to make sure that absolutely nothing happens to it until the case is over.

Archiving rules, retention rules, legal hold: all of these are covered by our archiver and can be configured with high precision and granularity taking advantage of an advanced graphical query builder.


10- Granular permissions

Granular role management

Granular role management

Who can do what? You should get to choose, without any limitation. The permission system must adapt to your current and future policies, not the other way around.

Besides the “standard” roles of admin, auditor and user, on our archiver you can create custom roles in a very granular way. A role is basically a collection of capabilities and there are about 80 different capabilities that you can assign to any role you need.


Phishing campaign uses Google reCAPTCHA to avoid Sandbox detection

Recent email phishing campaigns are using Google reCAPTCHA as part of their efforts to bypass click-time protection sandboxing, requiring user interaction before delivering the actual contents of the phishing page.

We have seen two different instances of such campaigns, both are targeting Office 365 users in order to collect their credentials. Implementation details suggest that the two campaigns are not coming from the same actors.

In both instances, as soon as the user clicks on the link contained in the email and the browser lands on the page, a Google reCAPTCHA is displayed in an otherwise empty page:

This is intended to act as a barrier for automated scanning services, letting only humans go through this first step.

The phishing web application is built using React, a widely used javascript framework. The level of skills required is well above the average for such phishing campaigns.

The source code of the reactjs phishing application

After the reCAPTCHA has successfully confirmed that the visit comes from a human, then the real phishing page is displayed:

Phishing campaigns keep improving. Evading the inspection from bots increases the longevity of the phishing site by delaying the moment the website is blacklisted and browsers start displaying red warnings to users visiting it. In this case the phishing site is still online and not blacklisted after more than 5 days at the following domain infiniteaudiovisual[.]com.

Here is a video of the whole process:


URL sandboxing services like Libraesva URLSand, by visiting the page at click-time, can afford to make deeper checks on the contents of the website and on it’s behavior in reaction to real clicks originated from real phishing emails.

Besides searching for phishing toolkits and patterns, besides semantic analysis and heuristics, besides reputation checks and machine learning, our URLSand actively seeks for evasion and obfuscation attempts.

Evading detection is crucial but it provides useful signals to the expert analysis of specialized automated security systems which are continuously kept up to date by our Esvalabs team.

This is the approach that allows our URLSand to block this and similar threats.



What is the Libraesva QuickSand Sandbox

The Libraesva Quicksand Sandbox is a security service that protects the Libraesva customers from malicious active content in Microsoft Office and PDF Files.

  • What is active content?

Active content is any executable code embedded in a document, like macros, JavaScript code and ActiveX applications.

Quicksand runs on our Email Security Gateway, for free, meaning that files never leave the gateway.

As the name suggests, the sandbox is very quick and efficient, the attachments are analysed at the same time as the generic email analysis with no delays and isn’t vulnerable to traditional sandbox evasion techniques.

Quicksand identifies active content inside documents and classifies it based on the behaviour, these categories of behaviour are categorised as:

  • Safe: Active content is present and it does not perform any critical operation in respect to security
  • Suspicious: Potentially critical actions are performed by the active content like downloading data from the internet, launching programs, performing actions on the file system and so on
  • Indeterminate: Active content is present but for technical reasons it’s behaviour cannot be categorised with enough accuracy
  • Encrypted: The document is encrypted and therefore it is not possible to tell whether there is active content inside

For each of these categories, you can choose what to do with the file:

  • Deliver: deliver the file as is
  • Sanitize and deliver: disarm the active content and deliver the disarmed document
  • Block: do not deliver the file, it will be removed from the email

Not all of the actions are available for all of the categories, for safety reasons. You can also define fallback actions in case the document cannot be sanitised for technical reasons.

Hopefully this blog post helped you understand a bit more behind our key product feature QuickSand. Please contact us if you need any additional information, or follow this URL here

Which will showcase the feature in a bit more technical depth.

What’s the difference between email backup and email archiving?

Lots of differences, actually.

An email backup is a snapshot of a specific point in time, it’s purpose is for recovery in case of a disaster. Email archiving does not archive a series snapshots but it preserves all data history. The purpose of the archiver is much broader: discovery, compliance, legal, search, analysis and for regulatory and policy obligations.

For example: emails that have been sent or received and then deleted before the backup has been taken, are not available while they are present in the email archiver. Every email enters the email archiver in real time, as soon it is transmitted or received, and frozen there. Quite different from a snapshot.

While a backup data retention policy can only be based on age of data, the data retention policy of the email archiver is very flexible and can be based on age, content, metatada and legal-hold status.

There are also practical conveniences in using the archiver: emails can be automatically deleted from the mailserver in order to reduce it’s load. You can keep only one or two years of email in your mailserver, older emails are still are available on the archiver with even greater search speed and more flexibility of access: the Outlook plugin, the mobile apps, the web interface.

Basically, you can think at the backup as something for administrators while archiving is mostly for users.

As soon as an email is received by the archiver it is hashed, timestamped and certified (RFC3161) providing historicity and valid legal proof of existence and integrity. Whenever that email is retrieved the certified timestamp is verified. The validity of the certified timestamp can also be assessed by third parties using non-proprietary tools.

Full-text search on email content, attributes and metadata enables efficient discovery. Complex searches returning hundreds of thousands of items are performed typically within 0.1 seconds.

Retention periods can be optimized for different email categories: for example email pertaining the organization core business can have a different retention time than bulk email.

Legal hold allows preventing email related to legal cases from being deleted for any reason, until the specified period.

Summarizing: the email archiver provides much more than a backup: not a recovery tool in the hands of the administrators but a production and compliance tool for the whole company.